Electronic Design

MCUs Sift Through Overlapping Solutions

The microcontroller market is getting larger and more confusing, but oh, the choices! All processor segments from 8 to 64 bits are growing both at the low and high ends, leading to considerable overlap. Increased demand for connectivity has also led to more choices as vendors incorporate 100-Mbit/s Ethernet on-chip. Finally, greater connectivity requires higher levels of security, pushing the need for more hardware.

Small, very low-power applications continually insist on 8-bit solutions. But overlap remains, even at the low end. Texas Instruments' 16-bit MSP430 still gives 8-bit solutions a run for their money in low-power applications. Look for even more competition in the 8-bit, high-performance analog arena, with products like SiLabs' 8-bit 8051 and its dual 16-bit analog-to-digital converter (Fig. 1).

The 16- and 32-bit MCUs are open to more competition as they get hammered by 8- and 64-bit solutions, along with the usual 16- and 32-bit overlap. Larger peripherals like Ethernet interfaces and large flash memory arrays overshadow the processor implementation in terms of die size, making application data size manipulation a major factor when choosing processor size.

Smaller architectures are improving pointer manipulation, while larger architectures concentrate on enhancing bit and byte handling. A hot area this year involves the emerging 16-bit digital signal controllers, apt to be used as general 16-bit processors because they handle signal control features.

Arm-based solutions will flow as many developers consider a jump from 8- to 32-bit architectures. Vendors of standard Arm-based parts are taking different approaches to better interrupt handling and bit manipulation. Likewise, software-development tools are getting a boost to handle the increase of on-chip peripherals in these MCUs.

Look for a plunge in the cost of evaluating a new component like NEC's 32-bit V850ES MCU (Fig. 2). Competition is a wonderful thing, and almost every MCU vendor offers evaluation kits well under $200. This includes a complete software suite, often with a C/C++ compiler. Open-source software, such as GCC and Eclipse, also has helped minimize a vendor's cost and development effort.

Ethernet-based MCUs will be popular this year, but they'll be joined by many other connectivity contenders. CAN-based (controller area network) MCUs continue to find uses outside of the growing automotive space, and I2C control networks are landing in more systems like Advanced TCA.

Freescale's 9S12NE64 Web server epitomizes what's in store this year (Fig. 3). It incorporates an Ethernet media-access controller and physical layer with a 16-bit HSC12 processor. Look for more gateway implementations that mix two networking interfaces (e.g., Ethernet and CAN) on one chip.

ZigBee, the low-speed wireless protocol, is out in force as a two-chip solution now. The MCU is typically connected to the RF transceiver chip via a serial peripheral interface. Look for this to continue until the high- and low-speed versions of ZigBee are well established. Don't expect too many production-available single-chip solutions this year, but they're on the way.

Two-chip solutions will remain the low end for MCU applications employing 802.11x. Complexity remains too high, and a single protocol has yet to emerge because many developers are still working with 802.11b.

Secure flash or EEPROM is expected to infiltrate more low-end MCUs. This is the minimum necessary for software security support. Up the ladder, you'll find MCUs with hardware encryption and secure memory implementations that utilize hardware controls. They will typically support connection protocols like SSL (secure sockets layer). Hardware support should be readily available this year, but a lack of standards above the encryption level will force early adopters to do their homework.

PACKAGING PERFORMANCE
The multiple-processor-MCU trend will continue at the high end, with possible opportunities in the 32-bit arena. Multiple processors offer higher performance as well as quicker interrupt handling.

Products like Broadcom's 64-bit MCU pack four processors into a single package (Fig. 4). A number of dual-processor solutions are also showing up, including products like Analog Devices' dual-BlackFin DSP. Developers can expect to discover high-performance interfaces like PCI Express, HyperTransport, and RapidIO. PCI Express will also start to replace PCI interfaces, but at a slow pace this year. That's because the PCI/PCI-X interface for embedded applications isn't going away any time soon.

Don't expect it in low-end, 8- and 16-bit solutions, but look for USB (Universal Serial Bus) Full Speed (12 Mbits/s) to be quite common. This includes USB OTG support.

1. High-performance analog can be found even in 8-bit MCUs like this 8051-based unit from Silicon Labs. The evaluation board shown here provides access to the pair of high speed, 16-bit analog-to-digital converters.

2. It's getting easier to evaluate high-performance microcontrollers like NEC's V850. Low-cost development boards with matching development software get designers started earlier.

3. Packing Ethernet onto an MCU is becoming more common. It allows a single-chip solution like Freescale's 9S12NE64, though the network interface takes up a considerable amount of real estate.

4. Broadcom packs four 64-bit processors on a single chip. But even more important are its high-speed interconnects. The ZBbus provides bandwidth for processors and a wide range of high-performance peripheral interfaces. A separate high-speed switch handles the HyperTransport (HT)/SPI-4 interfaces. The bridge memory interface implements NUMA (non-uniform memory access).

TAGS: Freescale
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